Puffing is the best medicine

May 04, 2006

The Food and Drug Administration is contradicting itself. It recently reiterated its position that cannabis has no medical utility, but it also approved advanced clinical trials for a marijuana-derived drug called Sativex, a liquid preparation of two of the most therapeutically useful compounds of cannabis. This is the same agency that in 1985 approved Marinol, another oral cannabis-derived medicine.

Both Sativex and Marinol represent the "pharmaceuticalization" of marijuana. They are attempts to make available its quite obvious medicinal properties — to treat pain, appetite loss and many other ailments — while at the same time prohibiting it for any other use. Clinicians know that the herb — because it can be smoked or inhaled via a vaporizer — is a much more useful and reliable medicine than oral preparations. So it might be wise to consider exactly what Sativex can and can't do before it's marketed here.

A few years ago, the British firm GW Pharmaceuticals convinced Britain's Home Office that it should be allowed to develop Sativex because the drug could provide all of the medical benefits of cannabis without burdening patients with its "dangerous" effects — those of smoking and getting high.

But there is very little evidence that smoking marijuana as a means of taking it represents a significant health risk. Although cannabis has been smoked widely in Western countries for more than four decades, there have been no reported cases of lung cancer or emphysema attributed to marijuana. I suspect that a day's breathing in any city with poor air quality poses more of a threat than inhaling a day's dose — which for many ailments is just a portion of a joint — of marijuana.

Further, those who are concerned about the toxic effects of smoking can now use a vaporizer, which frees the cannabinoid molecules from the plant material without burning it and producing smoke.

As for getting high, I am not convinced that the therapeutic benefits of cannabis can always be separated from its psychoactive effects. For example, many patients with multiple sclerosis who use marijuana speak of "feeling better" as well as of the relief from muscle spasms and other symptoms. If cannabis contributes to this mood elevation, should patients be deprived of it?

The statement that Sativex, "when taken properly," won't cause intoxication hinges on the phrase "when taken properly." "Properly" here merely means taking a dose — by holding a few drops of liquid under the tongue — that is under the level required for the psychoactive effect. As with Marinol, people who want to use Sativex to get high will certainly be able to do so.

One of the most important characteristics of cannabis is how fast it acts when it is inhaled, which allows patients to easily determine the right dose for symptom relief. Sativex's sublingual absorption is more efficient than orally administered Marinol (which requires 1 1/2 to two hours to take effect), but it's still not nearly as fast as smoking or inhaling the herb.

That means "self-titration," or self-dosage, is difficult if not impossible. Further, many patients cannot hold Sativex, which has an unpleasant taste, under the tongue long enough for it to be absorbed. As a consequence, varying amounts trickle down the esophagus. It then behaves like orally administered cannabis, with the consequent delay in the therapeutic effect.

Cannabis will one day be seen as a wonder drug, as was penicillin in the 1940s. Like penicillin, herbal marijuana is remarkably nontoxic, has a wide range of therapeutic applications and would be quite inexpensive if it were legal. Even now, good-quality illicit or homegrown marijuana, which is, at the very least, no less useful a medicine than Sativex, is less expensive than Sativex or Marinol.

The "pharmaceuticalization" of marijuana has promise. No doubt the industry could produce unique analogs of the naturally occurring cannabinoids that would be useful in ways smoked cannabis is not. But for now, medicines such as Sativex provide only one advantage over the herb: They're legal.

I have yet to see a patient who preferred Marinol to smoked marijuana. Similarly, the commercial success of Sativex will largely depend on how vigorously the marijuana laws are enforced. It is not unreasonable to believe that drug companies have an interest in sustaining the prohibition against the herb.

Geoffrey Guy, who founded GW Pharmaceuticals, claims his aim was to keep people who find marijuana useful out of court. There is, of course, a way to do this that would be much less expensive — both economically and in terms of human suffering.

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LESTER GRINSPOON is an emeritus professor of psychiatry at Harvard Medical School and the author of Marijuana, the Forbidden Medicine (Yale University Press, 1997).